Accessing the key_modifier property for a key binding
I found your question looking for the same issue. I found how to do it by looking at the code of Power Sequencer add-on.
After you define your shortcut you have to add a property to the keymap:
kmi = km.keymap_items.new(OPERATOR.bl_idname, 'LEFT_ARROW', 'PRESS')
setattr(kmi.properties, 'bool_property', True)

Then read that property from the operator:
class OPERATOR(Operator):
    bl_idname = &quot;operator.id&quot;
    bl_label = &quot;One operator&quot;
    bool_property: bpy.props.BoolProperty(
        name=&quot;A property&quot;, description=&quot;Does something&quot;, default=False
    )

    def execute(self, context):
        print(self.bool_property)

The operator's property you define retains its value after you call it from the shortcut, so remember to restore the property to its default value (or whatever you need) after the operator is called.